Implantable stimulation devices have been developed to provide therapy for a variety of disorders, as well as for other treatments. For example, implantable stimulation devices can be used to stimulate nerves (such as the spinal cord), muscles, or other tissue. An implantable stimulation device typically includes an implantable control module (with a pulse generator), one or more leads, and an array of stimulator electrodes on each lead. The stimulator electrodes are implanted in contact with or near the nerves, muscles, or other tissue to be stimulated. The pulse generator in the control module generates electrical pulses that are delivered by the electrodes to body tissue. As an example, electrical pulses can be provided to the dorsal column fibers within the spinal cord to provide spinal cord stimulation.
The stimulator electrodes are coupled to the control module by the lead and the control module is typically implanted elsewhere in the body, for example, in a subcutaneous pocket. The lead is often anchored at one or more places in the body to prevent or reduce movement of the lead or stimulator electrodes within the body which could damage tissue, move the stimulator electrodes out of the desired position, or interrupt the connection between the stimulator electrodes and the control module.